The structures that are very routinely used in architecture, in civil engineering structures and generally in fields linked to mechanics must generally suffer mechanical stresses that can evolve over time. These stresses cause deformations in the volume of these structures that can lead to their mechanical characteristics being degraded. To monitor the qualities of these structures it is necessary to be able to measure the evolution of the deformations that are produced in the volume of these structures.
The evolution of the deformations of the structures and the estimation of the stresses that they suffer may be tracked by devices placed on the external surface of the structures such as visual indicators for the deformations or mechanical sensors responsive to the deformation at the surface of these structures (FR2855210). The deformation within the volume itself may be estimated by integrating a uniaxial sensor or “measurement fiber” such as an optical cord into the volume of the structure itself (WO2006127034). However, these methods at best make it possible to estimate only a mean value along the axis of the sensor of the components of the stresses or deformations in a fiber placed in the volume under surveillance. Finally, direct integration of a sensor into the volume under surveillance may lead to weakening of the structure that may be caused by the mechanical quality difference of the materials constituting the sensor or to modification of the distribution of the stresses in the volume of the structure in the vicinity of the sensor. In the latter case the particular shape of the sensor may lead to local stress concentrations liable to cause the onset of cracking in the vicinity of this sensor. Moreover, the modification of the stress distribution in the vicinity of the sensor compromises the quality of the measurement, with the risk of it no longer ideally reflecting the magnitudes that it is required to measure [which may lead to using these sensors as threshold warning devices rather than as systems for effecting the tracked measurements].